Find the Public Hostname of an Amazon EC2 Instance

If you need to find the public hostname of an Amazon EC2 instance, there is a simple URL which, when cURL'ed will return the hostname:

http://169.254.169.254/latest/meta-data/public-hostname

This URL only works inside the AWS infrastructure (so you must be on an instance to run it properly), but you could easily run:

curl http://169.254.169.254/latest/meta-data/public-hostname

This will return the hostname in the standard format:

ec2-54-123-256-12.compute-1.amazonaws.com